Hydrothermal Synthesis of Nanostructured Titania

Abstract:

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Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150°C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H2Ti3O7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders.

Abstract: The crystallization behavior and microstructure of Li+-doped TiO2 thin films prepared by sol-gel dip coating were investigated by means of differential themal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization apparent activation energy (E) both in the absence and in the presence of Li+ ion was also measured with Kissinger method. As a result the E values of Li+-doped TiO2 thin film were decreased, thus the crystallization of non-crystalline to anatase and antase to rutile was promoted.